[libvirt-users] weird "no supported architecture for os type 'hvm'"

Hi, I have two identical machines with exactly the same CentOS 5.4 kickstarted from the same sources, and the same packages installed. Their cpuinfos are identical, and they are running libvirt 0.6.3 with the very same libvirtd.conf. Yet... One of them works fine, the other says "no supported architecture for os type 'hvm'" for the same template (attached) and image. Any thoughts on what kind of defect or misconfiguration could cause this? Thanks much! --Claude